The present invention relates to fluid valves, and, particularly to fluid valves that are electrically controllable and allow for automatic self draining upon removal of supply fluid pressure from the valve.
Electronically operated valves that control fluid flow in an on/off manner are used in many applications. Electronically operated valves that use a diaphragm to control fluid flow wherein the diaphragm deflects in response to hydraulic forces formed by the flow of fluid through the valve are known in the art as a diaphragm valve. One example of such a prior art valve is depicted as reference number 10 in FIGS. 1-3. The valve involves a diaphragm 103 that is in contact with an opening or diaphragm seat 108 formed on an outlet tube 110 and which has a lower surface 114. The valve 10 has a solenoid armature 105 that plugs a control opening 112 in the middle of the diaphragm 103. The control opening is also located over the outlet tube opening 108. When fluid supply under pressure is applied at the inlet tube 101, the diaphragm top surface 113 (in the orientation shown in FIG. 1) is exposed to a fluid pressure approximately equal to the supply fluid pressure because the fluid delivered to the inlet tube 101 is in communication with the diaphragm top surface 113 through rim hole 104. Rim hole 104 is located remotely from the outlet tube opening 108 and has a diameter smaller than control opening 112. The entire diaphragm top surface 113 is exposed to fluid pressure that is approximately equal to the supply pressure, while only the area of the diaphragm bottom surface 114 that is not within the outlet tube opening 108 is exposed to the same pressure. Since more area of diaphragm top surface 113 is exposed to the supply pressure than diaphragm bottom surface 114, the diaphragm 103 is forced into contact with and a seal is formed between the diaphragm 103 and the outlet tube opening 108.
When the solenoid armature 105 is retracted into the solenoid cavity 115 through the application of current to the solenoid coil 107, the control opening 112 allows fluid from the upper chamber 111 to drain into the outlet tube 110 because the pressure in the outlet tube 110 is less than the supply pressure in the inlet tube 101. Since the size of the rim hole 104 is smaller than the control hole 112, more fluid passes out of the upper chamber 111 and into the outlet tube than is admitted through the rim hole 104. This results in a drop in pressure (and resulting force) against the diaphragm top surface 113, thereby resulting in a lifting of the diaphragm 103 by the pressure along the diaphragm bottom 114, thus causing the valve to open.
Once the valve is in the open state, i.e. the diaphragm 103 is away from the outlet tube opening 108, the flow of fluid between the outlet tube opening 108 and the diaphragm bottom 114 results in a drop in fluid pressure near the outlet tube opening 108. If the solenoid armature 105 is re-engaged into the control hole 112, higher pressure will again develop along the diaphragm top 113 by fluid entering the rim hole 104 and combined with the lower pressure along the diaphragm bottom 114, the diaphragm 103 will re-engage the outlet tube opening 108, thereby closing the valve.
The prior art valve in the instant example utilizes a diaphragm 103 that is designed and located so as to be stable in one of two states. When supply fluid pressure is present and the solenoid armature 105 is engaged into the control opening 112 of the diaphragm 103, the diaphragm 103 remains in the down, or closed, state. When supply fluid pressure is present and the solenoid armature 105 is removed/lifted from the control opening, the diaphragm 103 moves xe2x80x9cupxe2x80x9d, or to the open state. Upon removal of supply fluid pressure, the diaphragm 103 returns to the xe2x80x9cdownxe2x80x9d state wherein the diaphragm 103 re-engages the outlet tube opening 108. FIGS. 2 and 3 also demonstrate diaphragm 103 resting atop diaphragm seat 108 in a relaxed state whether or not armature housing 403 is placed in sandwiching relation thereupon, in the absence of supply fluid pressure. That is, in the prior art valve shown in FIGS. 1, 2 and 3, diaphragm 103 remains in sealing engagement with seat 108 in the absence of input fluid pressure in inlet tube 101 and with or without the influence of armature 105.
The prior art valve illustrated in FIG. 1 remains xe2x80x9cclosedxe2x80x9d even when the supply fluid pressure is removed. In some applications, such as in hot tubs and whirlpool baths, the fluid may contain undesirable material such as bio-matter. Allowing the fluid with this undesirable matter to remain in the closed valve and associated tubing for an extended period of time may result in contamination of the fluid, valve and tubing and an unsanitary condition.
It is to be noted that this short coming in presently available valves applies to virtually any type of valve, not just diaphragm valves. All valves, gate valves, and all the others known to those of skill in the art, are designed so as to prevent fluid flow across the valve boundary when the valve is in its closed state. Consequently, use of any such pre-existing valve in applications such as those referenced above is less than desirable.
It is an object of the present invention to provide an improved valve design that automatically provides for drainage of the valve upon removal of supply pressure.
In its preferred form the invention employs a modification of the prior art valve shown in FIGS. 1-3 such that the diaphragm, in its xe2x80x9cat restxe2x80x9d position (as shown in FIG. 6), namely, when the supply fluid pressure is equal to or approximately zero, is spaced from seat 108 a distance sufficient to readily permit the flow of supply fluid from inlet conduit 101 to outlet conduit 110. In this way, when the flow of liquid is discontinued through the valve, any remaining liquid in the valve can freely drain, also permitting the entire system of conduits to which the valve is connected to drain as well.
The existing valve can be modified by lowering the position of the seat 108 relative to the at rest location of the bottom surface 114 of diaphragm 103, raising the lower surface 114 of diaphragm 103 relative to seat 108, or permitting the position of one or the other to be adjusted depending upon the viscosity and other characteristics of the supply liquid.
The present invention achieves this and further objectives by providing a valve having three stable states. When input fluid pressure is applied and the solenoid is de-energized, the diaphragm seats against seat 108, terminating flow through the valve, as with prior art valves. When input fluid pressure is applied, and the solenoid is energized, fluid can flow between volumes 101 and 109 as in the prior art. However, when input fluid pressure is removed, the valve is constructed so as to cause the diaphragm to enter a third, stable, state wherein the diaphragm does not seat against the orifice seat 108 of the outlet tube, but is partially removed from that orifice, causing the valve to remain open so that fluid on either side of the diaphragm can drain off.